Python Sets Tutorial #2 - Methods

Key Takeaways

in this video I'm gonna be going over some useful set methods and continuing to talk about sets more detail than showing you some more advanced things that you can do with them if you haven't seen my previous video just talking about how a set works it's an unordered unique data set or collection of elements sorry I recommend you go watch that if you already know about sets then just stay here and I'm just gonna go through some really useful methods and pretty much wanted me to talk about are here right in this little box so feel free to just read through them and kind of experiment with them yourself but if you want a more like in-depth kind of tutorial on them then watch through the whole video I'm going to go through what all of these do and how they work so sets are really useful in Python because they come with a lot of methods and if any of you guys are in linear algebra then you know that there's a lot of things you want to do with sets like subsets super sets differences intersections unions and those can be annoying to have to code yourself so yes you can code them yourself just using typical lists but these sets allow you just to type like one method and have it all done for you and it saves you a lot of time it also just looks cleaner in your code so I'm going to start by creating two sets so I'm just going to say s is equal to like 1 2 3 7 & 8 and why not just a little string in here we'll do a test I'm going to do a set T I'm gonna set this equal to 3 4 5 8 9 tests like this okay now one of the most useful methods that you can use on sets is I would want to say intersection and intersection is gonna give you the most or any elements that are in both of the sets and this is really useful there's a lot of applications and so I'll show you how you can do it you can do s dot intersection of T like this and what this is gonna do is it's gonna return a new set containing all of the elements that are common within set so when I do that you see we get 8 test and 3 and those are because they occur in both sets another one that's really useful is Union and what this does is it simply just combines all of the elements in the set together so if I do s dot Union T then you can see we get all of the elements combined together and notice because it's a set we don't have any duplicate elements it just finds ones just like bushes these two sets together another one that's useful is is subset so I'm gonna just create a small set anesthetic SS is equal to like 1 2 3 that's not a set is it it's a list of my bad because we're not gonna be able to use this on list so SS equals that and we'll just do like TT equals and let's do 1 2 now if we want to determine if TT is a subset of SS there's a way that we can do this we can say is is subset is actually the method so say SS or TT DUT is subset of SS and that gives us a true value and the way that this works is it pretty much finds and our it looks at TT and says are all the elements in TT also contained in SS and if they are then that means this is indeed a subset of the set SS ok so let's do this again except let's just change this around so SS is SS a subset of TT well I'll let you guess by having a look and the answer is no and that is because if we look at SS is every element SS in TT no it's not so this is going to give us a false value now another one that we can use is is superset and it's kind of just like a reverse of this so if I do ss is superset of TT now it's going to check and see if all the elements in TT are in SS so it's doing the same thing as is subset just kind of in Reverse so it's giving us a true value now so that means that this contains all the elements that are in like the lower bound set kind of so again if we flip this around we do TT SS we get false ok so another one that's really useful is difference and what difference is gonna do it's gonna give us all the elements that are in one set but are not in the other so if I say s dot difference I'm going to go back up to these tops that's now and use these I start difference of T then we get set of one two and seven so these are the elements that are in s that are not in T and same thing if we do TDOT different s then we get the elements that are in T but our 9s and again that's useful as well you want to find elements that aren't common to both sets now we can also do something called a symmetric difference and with some symmetric difference does is it's going to find elements that aren't in either of these sets okay so if we do symmetric difference of T then we get one two four five seven nine and the way that symmetric works is it finds the elements set like aren't in common with the set so you can see one does not exist in this set two does not exist in this set three does we don't get three and four well that doesn't exist in the other set so we add four five doesn't exist in the other sets we had five seven eight does exist so nice so it finds all the elements that are not common in both of the sets and combines them into a new set now it's good to notice here what these are doing is they're returning us a new set and we can see that because they're printing it out to the screen so it's not actually changing s and it's not changing T and I can press NT it's just returning a new set now the last one I'm going to show you this is pretty straightforward since sets are mutable sometimes you may want to make a copy of them and you can't actually RL test but I'm pretty sure you can't do something like this so set H equals s : yeah we get an error so that would be how you copy lists so how do you copy a set the way to copy a sent is through H is equal to s con copy now for any of you guys that are a bit more advanced this is creating a shallow copy of s you don't have to know what that means but I'm just giving it to you guys in case that means something to you so that's how you would make a copy so now if you change something in H sources like each dot remove what's in s let's see like one and we print H and then we print s we can see we did not end up changing s because we made a copy anyway so that's been it for some of these useful set methods if any of you guys are in linear algebra I hope you appreciate these because coding these can be kind of difficult and also just take a lot of time so these methods save you a ton of time and just help you out when programming anyways that's been it for this video if you guys enjoyed please make sure you leave a like and subscribe and I'll see you again in another one [Music]